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Cover Crops after Corn Silage, Planting Early by Interseeding


Hi I’m Heidi Johnson the Dane County
crops and soils educator for the University of Wisconsin Extension. We
grow a lot of corn silage in Wisconsin and it’s one of the most important
places that we can use cover crops. This is because the harvest of corn silage
leaves very little residue, so cover crops can play an important role in
preventing soil erosion. Corn silage harvest also results in taking off a lot
of carbon. Cover crops give us an opportunity to return carbon to the soil
and protect soil organic matter. Lastly corn silage ground often receives
a manure application. Using cover crops can help us keep manure in place so it’s
not leaving fields and causing environmental damage. It also helps to
keep manure in place so we can take nutrient credits and offs of some of our
fertilizer costs. Because corn silage is harvested so much earlier than corn for
grain and soybeans it provides us an opportunity to grow cover crops for a
longer period of time in the fall. this also gives us more choices for cover
crops so generally we recommend several key cover crops for use after corn
silage. oats or barley are two cover crops that are going to die out over the
winter and then triticale rye and wheat our three cover crops that are going to
survive the winter. all of these cover crops work well
because they can grow down to a very low degree so they can grow for as long as
possible in the fall they all provide good winter cover for the soil to
prevent soil erosion. because oats and barley will die out during the winter we
do want to make sure those get planted as early as possible. our general rule is
for farmers to try to get them in by early to mid-september. We can do that a
couple different ways with a ground rig like a highboy or also aerially apply
with a helicopter or an airplane. the nice thing about aerially applying
coverage since that it doesn’t depend on soil
conditions for the helicopter or the airplane to be able to run. the important
thing to remember when you see cover crops into a standing corn silage crop
is that you need moisture because the cover crop is just landing on the soil
surface you need a good rain after seeding to have it help the cover crop
get up and start growing if it doesn’t rain the cover crop seed will tend to
just sit there. the other thing to remember is that the corn silage needs
to be harvested in a timely manner we often recommend that farmers try to seed
no more than two weeks prior to corn silage harvest. This is because it’s very
dark in the corn silage canopy and the cover crop really struggles for light if
it goes for more than two weeks. What we see as the cover crop gets very very
long and then tends to run out of sunlight and falls over in the canopy
and doesn’t survive so we recommend that farmers try to time things out that
their corn silage harvest is no more than two weeks before they’re going to
get the cover crop seeded. This is a spring barley cover crop that was seeded
by airplane 14 days ago today this silage field is getting harvested today
and you can see the cover crop looks a little bit spindly from lack of sunlight
but now that the corn silage is being taken off it’s going to get plenty of
sunlight and it’ll start to grow really quickly and cover the field. The nice
thing is that we don’t have to wait for the cover crop to get seeded now after
harvest it’s already here has a head start and can take advantage of the rest
of the season

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